The present invention relates to an abnormality detection device for a fan which cools a lamp or a board of a liquid crystal projector or the like.
Various types of abnormality detection device for a fan which cools a lamp or a board in a liquid crystal projector or the like have been proposed in the prior art.
For example, with the device disclosed in Japanese Laid-Open Patent Publication 2005-107276, there are included a temperature sensor which detects that the temperature has risen to an abnormally high level, and a rotation sensor for the fan, and predetermined abnormality processing is performed for detecting an abnormal state of the fan, based upon the signals detected by those sensors. Moreover, with the device disclosed in Japanese Laid-Open Patent Publication Heisei 7-295098, an abnormal state of the fan is detected based upon the output of a rotation detector of the fan.
However, in the case of both of the devices disclosed in the documents described above, it is detected whether or not the rotation of the fan stops, but the cause of this stopping is not detected. Furthermore, it also has not been possible to detect a situation such as one in which the fan is loose and slipping, or a vane has broken off, or the like.
Since, in this manner, with fan abnormality detection devices such as have been proposed in the prior art, the cause for the rotation of the fan stopping and the detailed situation have not been detected, accordingly there has been the problem that, when an abnormality has been detected, it is not possible easily to ascertain the cause of this abnormality.
The object of this invention is to provide a fan abnormality detection device which detects the state of abnormality of the fan in detail, and with which countermeasures corresponding thereto become simple and easy.